Add factor to the effect of factored load

[mdesjardinsXJ286]

Hi,

How can we add a factor on the effect of the factored load on the structure? I am using Standard CSA S7 and I need to apply a factor on the load effect of a few load combination. See below. 

[Romanich]

Hi @mdesjardinsXJ286,

You can create manual combinations and assign a factor as a product of two factors.

[mdesjardinsXJ286]

Hi,

I am not sure about this approach. For example if I compare ELU COMB 1 and ELU COMB 2 (Wich are ultimate limit state combination) of the above I have:

ELU 1 = 1.2D+1.7L+0K
ELU 2 = 1.2D+1.6L+1.15K

I dont think using ELU 2 = (1.2*1.15)D+(1.6*1.15)L will give appropriate results. It's my understanding of your proposal (Let me know if I misunderstood).

My understanding of load K is the following (Based on excerpts from the standard translated by DeepL)

- Each load to be included in a load combination must be multiplied by the specified load factor and the induced load effects calculated. The factored load effects are then added together to give the total factored load effect.

- K=All stresses, strains and displacements and their effects, including the effects of restraint.

My understanding of ELU 2 is I need to get results from 1.2D+1.6L and then apply 1.15 factor on all effects resulting from that particular loading. Do you think I am correct? Do you know any way of doing this in ROBOT other than extracting all results in excel and applying 1.15 factor manually ?

[Romanich]

Hi @mdesjardinsXJ286,

According to the design code, K is a load type and "K = all strains, deformations, and displacements and their effects, including the effects of their restraint and the effects of friction or stiffness in bearings. Strains and deformations include strains and deformations due to temperature change and temperature differential, concrete shrinkage, differential shrinkage, and creep, but not elastic strains."

In combination, ULS 2, I would use 1.15K only if I model temperature loads, for example, in the load case K.

[mdesjardinsXJ286]

Ok thanks! I am not using temperature load. It make sense as you point the ''but not elastic strains''. I am using the french version on the code and it's written a different way. Guess it is a bad translation.

Is your definition of K from the english version of CSA S6 or S7?

I am doing a suspended bridge and the bridge deformation under the load as an effect on the forces in the different members. So I tought I would have to factor the effect of bridge deformation.

[Romanich · Accepted solution]

I used the definition from CSA S6, but CSA S7 has the same one: